Fluorinated benzyl ether polymers and process for their preparation



United States Patent r 3,321,531 FLUQRINATED BENZYL ETHER POLYMERS ANDPROCESS FOR THEIR PREPARATION Robert Neville Haszeldine, Wind'yridge,Lyme Road, Disley, Cheshire, England, and John Michael Bircllall, 22Lorna Road, Cheadle Hulme, Cheshire, England No Drawing. Filed Sept. 13,1962, Ser. No. 223,553 Claims priority, application Great Britain, Sept.19, 1961, 33,566/ 61 19 Claims. (Cl. 260-613) This invention relates toorganic polymers and to methods for their manufacture.

The number of organic polymers which areknown is very great, and theiruse in many different applications is widespread. However, the number ofsuch polymers which can be made with relative ease and which are yetstable and resistant to chemical or thermal attack is surprisingly few.

The present invention provides a new'class of organic polymers whichhave high chemical and thermal stability and which are useful inapplications where extremes of temperature, pressure or chemical attackare likely to be encountered, for example, as molding materials,lubricants, or lubricant additives.

In accordance with the invention, polymers are provided which arecharacterized by the repeating unit:

where X is hydrogen, fluorine, or chlorine and each of R and R ishydrogen, a methyl group, a perfluoroalkyl group having not more thansay 20 carbon atoms; an aryl, fiuoroaryl or chloroaryl group. The four Xatoms may be the same or different and as indicated the groups mayappear at any of the positions on the ring.

Of particular interest are those species of the invention havingrepeating units of the general formula and especially polymerscharacterized by the repeating unit The polymers of the invention mayhave a wide range of molecular weights, embracing from say 2 to 10,000of the repeating units identified above.

In accordance with the invention, the novel polymers can be prepared byreacting a compound having the general formula with a strong base oralkali.

In the formula X, R and R are as defined above, Z is fluorine, chlorineor bromine and Y is chlorine, bromine iodine, acyloxy or hydroxyl. It ispreferred that Z as well as all four X atoms, be fluorine.

When Y is chlorine, bromine, iodine or acyloxy, it is necessary first toconvert it into a hydroxyl group. The base used must therefore have acation component capable of forming a salt with the anion:

Suitable bases include aqueous solutions of the hydroxides of the alkalimetals, particularly sodium and potassium and of the alkaline earthmetals, particularly calcium, Salts of these hydroxides with weak acidssuch as Na CO may also be used, and are intended to be included in theterm strong base as used herein.

When Y in the starting material is hydr-oxyl, the reagent used may beeither an aqueous solution of a strong base or of a salt of a strongbase weak acid as described above, or an alkali or alkaline earth metal,for example, sodium, potassium or calcium. The metal may be used withouta solvent, or with a non-aqueous solvent such as dioxane or diethylether.

The reaction may be carried out over a wide range of conditions. Thusthe temperature may be from say 20 C. to say 200 C., conveniently from 0to C. Pressure may range from say 1 to 200 atmospheres (absolute) and ispreferably between I and 5 atmospheres (absolute). The molar proportionsof the organic starting material (ZC X CRRY) to base or alkali metal isordinarily between about 1:5 and 5:1. When an aqueous solution of astrong base is used, the concentration is desirably in the range betweenabout .01 N and about 20 N, preferably between about 0.05 N and about 5N.

Conveniently the reaction can be carried out by refiuxing the startingmaterial (ZC X CRRY) with an aqueous solution of the base at about 100C.

It is preferred that Z and the -CRRY group should be in the paraposition in the starting material, and it is found in practice that,using the preferred starting materials in which every X, and also Z,represents fluorine, the polymer formed is joined up substantiallyentirely by removal of the para fluorine atom.

Thus, for example, when pentafluorobenzyl bromide is reacted withaqueous potassium hydroxide, a solid polyether is formed having theformula where It may be from I to say 10,000.

Cross-linked polymers can be produced by carrying out the reaction inthe presence of a compound of the type C F (CH Y) e.g.1,4-di(bromoethyD-tetrafluorobenzene.

The polymers provided by the present invention are new structural typesand as noted above have a high degree of chemical and thermal stability.They can therefore be used in various applications where theseproperties are required. For example, they can b added to lubricantswhich are to be used under extremes of temperature to improve theproperties of the lubricant, e.g. its viscosity, without danger ofdegradation or decomposition.

The pentafiuorobenzyl halide starting materials are readily preparedfrom hexafiuorobenzene by converting it, by the action of lithiummethyl, to 2,3,4,S,6-pentafiuorotoluene which is then treated with theappropriate halogen in the presence of light or ultra-violetirradiation. In a specific preferred embodiment of the invention, pentafiuorobenzyl bromide is first reacted with Na CO to formpentafluorobenzyl alcohol (with th production of a small amount of lowpolymer) and the alcohol is then further Polymer formation from2,3,4,5,6-pentafluorobenzyl bromide Pentaflu-orobenzyl bromide (5.00 g.;19.2 millimoles) is heated under reflux with potassium hydroxide (1.11g.; 19.8 millimoles) in water (30 ml.) for hours. The mixture isextracted with ether (4X 25 ml.) and the extracts washed with water,dried (MgSO and evaporated. The polymer (3.51 g.) is extracted withn-hexane. The soluble polymer fraction is recrystallized several timesfrom nhexane and gives a white solid (1.82 g.; 54% M.P. l02 104,identified as the polymer (Found: C, 45. 6; H, 1.5, C H F O requires C,45.5; -H, 1.3%). The infrared spectrum of this material is consistentwith the proposed structure.

EXAMPLE 2 Polymer formation from 2,3,4,5,6-pentafluorobenzyl chloridePentafluorobenzyl chloride (5.0 g.; 25.2 millimoles) is heated underreflux with potassium hydroxide (1.41 g.; 25.2 millimoles) in water (25ml.) for hours. The mixture is extracted with ether (4x 25 ml.) and theextracts washed with water, dried (MgSo and evaporated. The residualpolymer (3.71 g.) is extracted with n-hexane and the hexane-solublepolymer recrystallized from nhexane to give a solid polymer (2.6 1 g.;58%) M.P. 90- 100 C. with an infrared spectrum similar to that of thesample description above.

EXAMPLE 3 Preparation of polymer and 2,3,4,5,6-pentafluorobenzyl alcoholfrom pentafluorobenzyl bromide and sodium carbonate2,3,4,5,6-pentafluorobenzyl bromide (4.3 g., 0.016 mole) and sodiumcarbonate (8 g., 0.075 mole) in water (42 ml.) are heated under refluxfor 31 hours. The mixture is extracted with ether, and the extractsdried (MgSo and distilled under reduced pressure to give2,3,4,5,6-pentafluorobenzyl alcohol (2.7 g., 83%) M.P. 30-32, B.P.110116/52 mm., identified and shown to be pure by infrared spectroscopyand gas-liquid chromatography.

The residue from the distillation (0.3 g.) is dissolved in chloroformand the solution decolourised with animal charcoal. Removal of thesolvent then gives a pale yellow solid, shown by infrared spectroscopyto be the polymer C F -CH -O[-C F -CH -O-] -H.

EXAMPLE 4 Preparation of polymer from 2,3,4,5,6-pentafluorobenzylalcohol and potassium hydroxide 2,3,4,5,6-pentafluorobenzyl alcohol (20g., 0.01 mole) is heated under reflux with potassium hydroxide (1.0 g.,0.018 mole) in Water (*9 ml.) for 13 hours. The solid product isseparated by filtration, washed with Water (4x 25 ml.) and ethanol (2X25 ml.) and dried over phosphorus pentoxide in a vacuum desiccator. Theresulting pale yellow solid (0.8 g.), M.P. 182190, is

' mole) in water (15 ml.) for 36 hours.

identified as the polymer [-C F -CH -0] by infrared spectroscopy andelemental analysis. [Foundz F, 41. 5% (C I-I F O) requires F, 42.7%].The high chain length of the polymer is further indicated by the highmelting point, the very weak absorption at 3 1. in the infrared (showingthe small number of hydroxyl end-groups), and its complete insolubilityin ethanol, ether, chloroform, carbon tetrachloride, methylene chloride,dioxane, an

n-hexane. 1

EXAMPLE 5 Preparation of the polymer from 2;3,4,5,6- pentafluorobenzylacetate Pentafluorobenzyl acetate (2.0 g., 0.008 mole) is heated underreflux with potassium hydroxide (2.0 g., 0.036 The resulting solid isremoved by filtration, washed with water and ethanol, dried in a vacuumdesiccator, and identified as the polymer [C F -CH -O-] by infraredspectroscopy.

EXAMPLE 6 Preparation of the polymer from 2,3,4,5,6-pentafluorobenzylalcohol and sodium carbonate Preparation of the polymer from2,3,4,5,6-pentafluorobenzyl alcohol and potassium Metallic potassium isadded in small portions to a four molar excess of vigorously stirredpentafluorobenzyl alcohol heated under reflux on a steam bath. Themixture is heated at for 24 hours, an excess of water is added, and theunchanged alcohol is removed by distillation. The solid polymer isrecovered by filtration of the residue.

EXAMPLE 8 Preparation of starting materials2,3,4,5,6-pentafluorotoluene, an intermediate in the preparation of thestarting materials used in the examples above, may be made by one of twomethods:

METHOD 1 A cold (10 C.) solution of 0.82 M methyl lithium (0.258 moleMeLi) in tetrahydrofuran (317 ml.), prepared from methyl chloride, isadded to hexafluoroben- Zene (40.0 g.; 0.216 mole) in tetrahydrofuran(200 ml.) under nitrogen. The stirred mixture is cooled to 60 C. :5"throughout the addition (2 hours) and for 90 minutes afterwards, thenallowed to warm to 0 C. and poured into ice-cold water (600 ml.)containing hydrochloric acid (5 N; 80 ml.). The mixture is extractedwith petroleum ether (B.P. 3040; 4 200 ml.), and the extract dried (MgSOand fractionated to give 2,3,4,- 5,6-pentafluorotoluene (27.9 g.; 71%)(Found: C, 46.2; H, 1.7. C H F requires C, 46.1; H, 1.7%), B.P. 117-118/762 .rnrn. n 1.4023.

METHOD 2 No reaction is apparent when 5 ml. of a 1.4 M solution ofmethyl lithium in diethyl ether is added to hexafluorobenzene (44.5 g.,0.239 mole) in diethyl ether ml.) at 50 C. under nitrogen. The stirredmixture is allowed to warm to 20 C. when the separation of a blackprecipitate shows that reaction is beginning. The remainder of themethyl lithium solution (157 m1.; 0.226 mole MeLi total) is added overtwo hours, whilst the reaction mixture is kept at 15" C. :2". Themixture is stirred at 10 C. for a further 30 minutes, allowed to warm toroom temperature, and poured into ice-cold water (500 ml.) containinghydrochloric acid (5 N; 60

strong bases having cation components capable of forming salts with theanion (b) alkaline metals and (c) alkaline earth metals, at atemperature between about 20 and about 200 C. and at a pressure betweenabout 1 and about 200 atmospheres.

14. A method for making a polymeric product characterized by therepeating unit F F I I CH2O- I I F F which comprises reacting2,3,4,5,6-pentafluo-robenzyl bromide with an aqueous solution of astrong base having a cation component capable of forming a salt with theanion F F I I at a temperature of between about -20 and about 200 C. andat a pressure of between about 1 and about 200 atmospheres.

15. A method for making a polymeric product characterized by therepeating unit *CHP'O- I I F F which comprises reacting2,3,4,5,6-pentafluorobenzyl chloride with an aqueous solution of astrong base having a cation component capable of forming a salt with theanion F F I I at a temperature of between about '-2O and about 200 C.and at a pressure of between about 1 and about 200 atmospheres.

16. A method for making a polymeric product characterized by therepeating unit I 1 which comprises reacting 2,3,4,5,6-pentafluorobenzyla1- cohol with an aqueous solution of a strong base having a cationcomponent capable of forming a salt with the anion CH2O I F F 17. Amethod of making a polymeric product characterized by the repeating unitI I F F which comprises reacting 2,3,4,5,6-pentafluorobenzyl bromidewith sodium carbonate at a temperature of between about --20 and about200 C. and at a pressure of between about 1 and about 200 atmospheres.

18. A method for making a polymeric product characterized by therepeating unit I I F F FOREIGN PATENTS 269,973 4/1927 Great Britain.

BERNARD HELFIN, Acting Primary Examiner.

W. H. SHORT, Examiner.

H. D. ANDERSON, Assistant Examiner.

ml.). Separation of the ethereal layer, extraction of the aqueous layerwith ether (4X 100 ml.), and distillation of the dried (MgSO extractgives 2,3,4,5,6-pentafluorotoluene (30.2 g.; 69% identical with thecompound described in Method 1.

This compound may then be converted to pentafluorobenzyl chloride andpentafluorobenzyl bromide by the following procedures:

Chlorination of 2,3,4,5,6-pentafluorotoluene Pentafluorotolene (4.76 g.;26.2 millimoles) and chlorine (1.86 g.; 26.2 milli-moles) are sealed,under vacuum, into a 180 ml. silica tube and irradiated by a 250 w.mercury discharge tube for 3 hours. Hydrogen chloride is evolved. Theliquid products are washed from the tube with ether (50 ml.), and theethereal solution is washed with 2% aqueous sodium carbonate, 2% aqueoussodium sulphite, and water and dried (MgSO Distillation gives a fractionconsisting of pure 2,3,4,5,6-pentafluorobenzyl chloride (1.21 g.)(Found: C, 38.8; H, 0.9. C H ClF requires C, 38.8; H, 0.9%), B.P.l56-157/750 mm., n 1.4432. Chromatographic analysis of the remainingfractions shows the following total yields: pentafluorotoluene, 1.00 g.,21%; pentafiuorobenzyl chloride, 3.56 g., 63%; pentafluorobenzalchloride 0.59 g., 9%; products of B.P. 180, 0.2 g., 34%.

B'mmination of 2,3,4,5,6-pentaflur0t0luene Bromine (15.0 g.; 94.0millimoles) is added over 75 minutes to pentafluorotoluene (15.0 g.;82.5 millimoles), heated under reflux on a bath at 140 C. and irradiatedby a 100 W. incandescent bulb. Heating and irradiation are continued fora further 30 minutes, and the mixture is then cooled, dissolved in ether(50 ml.), and washed with 1% aqueous sodium hydroxide (50 ml.), 2%aqeous sodium sulphite (25 ml.), and water (50 ml.). The dried (Mg. S0ethereal solution is distilled to give pentafluorotoluene (0.76 g.; 5%),B.P. 1l6119, and 2,3,- 4,5,6-pentafluorobenzyl bromide (16.9 g.; 85%)(Found: C, 32.3; H, 0.9. c'7H2BI'20F5 requires C, 32.2; H, 0.8%), B. P,175-177/761 mm. n 1.4710.

Preparation of 2,3,4,5,6-pentaflu0r0benzyl alcohol The compound2,3,4,5,6-pentafiuoroben2yl alcohol may be made from the reaction of thecorresponding bromide and sodium carbonate as described in Example 3above. It can also be made by reacting 2,3,4,5,6-pentafluorobenzylacetate with sodium carbonate, as follows:

2,3,4,5,6-pentafluorobenzyl acetate (5.3 g., 0.022 mole) and sodiumcarbonate (3.0 g., 0.028 mole) in water (50 ml.) are heated under refluxfor hours. The mixture is then extracted with ether, and the extractsare dried (MgSO and distilled to give 2,3,4,5,6-pentafluorobenzylalcohol (3.4 g., 78%), B.P. 110-1'12/50 mm., identified by infraredspectroscopy and gas-liquid chromatography.

What is claimed is:

1. A polymer consisting essentiallyof a chain of from 2 to about 10,000repeating units having the formula l F F where R and R are hydrogen or amethyl group.

4. A polymer consisting essentially of a chain of from 2 to about 10,000repeating units having the formula 5. A method for making polymericmaterial which comprises reacting a compound having the general formulaat a temperature between about 20 and about 200 C. and at a pressure ofbetween about 1 and about 200 atmospheres.

6. The method claimed in claim 5 wherein the concentration of base isbetween about 0.01 N and about 20 N.

7. The method claimed in claim 5 wherein the Z and CRRY groups are inthe para position relative to one another.

8. The method claimed in claim 5 wherein the strong base is selectedfrom the group consisting of aqueous sollu tions of the alkali andalkaline earth metal hydroxides and the salts of such hydroxides withweak acids.

9. The method claimed in claim 5 wherein the strong base is potassiumhydroxide.

10. The method claimed in claim 9 wherein the strong base is sodiumcarbonate.

11. A method for making polymeric material which comprises reacting acompound having the general formula where Z is fluo-rine, chlorine orbromine, and R and R are hydrogen or methyl, with an alkali or alkalineearth metal, at a temperature of between about 20 and about 200 C. andat a pressure of between about 1 and about 200 atmospheres.

12. The method claimed in claim 11 wherein the Z and CRRY groups are inthe para position relative to one another.

13. A method for making polymeric material which comprises reacting acompound have the general formula hydrogen or a methyl group, with amaterial selected from the group consisting of (a) aqueous solutions ofUNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,321,531 May 23, 1967 Robert Neville Haszeldine et al.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 2, line 18, after "base" insert and line 52, for "bromoethyl"read bromomethyl column 6, lines 56 to 60, strike out R Z C-O- samecolumn 6, line 66, for "have" read having Signed and sealed this 11th'day of February 1969.

(SEAL) Attest:

EDWARD J. BRENNER EDWARD M.FLETCHER,JR.

Commissioner of Patents Attesting Officer

1. A POLYMER CONSISTING ESSENTIALLY OF A CHAIN OF FROM 2 TO ABOUT 10,000REPEATING UNITS HAVING THE FORMULA